Electrosurgical systems which use high frequency electrical current for cutting and/or coagulation of human tissue are well known in the art. Normally, the electrical current is applied to preselected tissue by using an electrosurgical instrument such as a unipolar electrode.
The typical unipolar electrode consists of a surgical grade stainless steel shaft or similar substrate that is substantially coated on its outer surface with an insulative (i.e., electrically nonconductive) coating. The tip of the substrate is exposed and defines the working surface of the instrument which may be configured in the shape of a hook.
During surgery, a conventional electrosurgical generator is used to energize the electrode substrate. The tip of the electrode is brought into contact with preselected tissue of a patient which results in a current path being provided between the electrode and the patient.
The current from the electrode develops a high temperature region about the electrode's tip which destroys tissue. The current is returned to the electrosurgical generator by means of a return electrode attached to the patient.
The widespread application and growth of electrosurgery has given rise to a large variety of specialized electrodes. For example, many surgical specialties (e.g., Neurosurgery, Cardiovascular surgery, General surgery, etc.) currently utilize some form of electrosurgery and hence electrosurgical instrumentation. As such, many different types of electrodes and electrode tip configurations are available such as a knife tip, cone tip, button tip, spatula tip, sling tip, scissor tip, forcep tip, and the like.
Although electrosurgery provides numerous advantages, there are several significant risks associated with electrosurgery. Numerous incidents of inadvertent electrical shocks and burns to the patient, and even death, have been reported. In a great number of these cases, the injury was due to the electrical insulation on the electrode shaft becoming worn, breaking down, or developing small pin holes. Thus, current is allowed to inadvertently pass from the electrode onto tissue or organs not intended to be altered.
Many materials used in providing electrode insulation typically lack durability. Illustrative insulation coatings consist of fluorocarbons such as poly (tetrafluoro-ethylene), a poly (vinyl chloride) (PVC), or a heat-shrinkable plastic. While these materials have well-documented electrical insulative characteristics, they are not optimally suitable for use with electrosurgical instrumentation. The major weakness of these coatings is their inadequate abrasion resistance (i.e., the coating rubs off easily leaving bare metal exposed), and decomposition of the coating at relatively high temperatures used in sterilization and in the electrosurgical process itself.
The lack in being able to detect whether an electrode that has been used in one or more surgical procedures still retains a reliable insulation coating necessitates the continued replacement of the insulation or the entire electrode. However, the risk of inadequate insulation on a new or refurbished electrode is still present because the insulation coating may have been defectively applied, damaged during shipping, or prematurely became worn-out.
Correspondingly, the present invention pertains to a device and method which detects defective electrosurgical insulation by providing for testing of the insulation before performing a surgical procedure.